Electrolysis mitigation



Jan. 22, 1924. 1,481,289 G. G. JONES ELECTROLYS IS MITIGATION Original Filed Sept. 24, 1920 IN V EN TOR.

6 207 G. Janey.

' ATTORNEY Patented Jan. 22, 1924.

UNITED STATES PATENT OFFICE.

GEORGE G. JONES, OF CAMBRIDGE, MASSACHUSETTS, ASSIGNOR TO AMERICAN TELE- PHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

ELECTROLYSIS MITIGATION.

Original application filed September 24, 1920, Serial No. 412,433. Divided and this application filed April To all whom it may concern" Be it known that I, GEORGE G. JONES, residing at Cambridge, in the county of Middlesex and State of Massachusetts, have invented certain Improvements in Electrolysis Mitigation, of which the following is a specification.

This ap lication is a division of a plication Scr. l o. 412,433 in the name of Eeorge G. Jones, September 24, 1920, for electrolysis mitigation.

This invention relates to the method of and means for protecting articles from the electrolytic action of earth currents.

Metallic articles, which are embedded in the ground, such as pipes, telephone and telegraph cables, building foundations, and other articles, are exposed to destruction by the chemical action of the soil and the elec trolytic action of roving or stray electric currents, sometimes known as earth currents. This destructive action is particularly apparent when the metallic articles are located in the vicinity of electric railway or power systems, as the currents utilized on such systems will flow from a grounded part, such as the track, of such a system, through the earth and enter the metallic article, such as the pipe at a point where its potential is negative with respect to that of the earth. At other points the potential of the article or pipe may be ositive with respect to earth and the roving or stray earth currents will escape from the article at these points and flow back into the earth. The current flowing from the earth into the acticle in general causes no damage and in some cases even protects the article it enters, whereas the current escaping from the article into the earth sets up an electrolytic action on the article from which it escapes. This action caused by the escaping current is known as electrolytic corrosion and will cause considerable destruction of the metallic article. K

The damage by electrolytic corrosion has in many instances assumed large proportions and many arrangements and methods have been devised and utilized to mitigate its effect. One method utilized has been to provide arrangements for lowering the potential of the article at such points, where it was positive to earth and the current Serial No. 556,931.

would escape therefrom into the earth, until the potentlal at such points would be neg ative with respect to that of the earth and the electrolytic corrosion at such points might be avoided. Another method utilized has been to provide arrangements for raising the potential of the earthabout the article, such as the pipe, so that the article at all points in the vicinity of the railway or power system would be of a lower potential than the earth and the earth currents would not have a tendency to escape therefrom and cause electrolytic corrosion.

It is the purpose of this invention to provide improved arrangements for raising the earth potential in the vicinity of parts of themetallic article at which electrolytic corrosion is apt to take place and to thereby mitigate or avoid damage at such parts. Other purposes and objects of the invention will appear more full from the following detailed description 0 the invention.

The arrangement is illustrated diagrammatically in the drawing, in the figure of which is shown a track 1 of an electric railway; a car 2 is mounted on the track and receives current from the feed wire 4, which is shown connected to the ositive bus of a generator 3, the negative us of which is connected with the track 1. A metallic article, such as the pipe or cable 6, is shown imbedded in the earth in the vicinity of the track 1. The path of the current from the power plant would nFmally be from the positive bus of generator 3, over wire 4, through the car 2, and back over the rails 1,

to the negative bu of the generator 3. A

portion of the current thus returning over the rails would leak off of the rails into the earth at points where the rails were of a higher potential than, or positive to the earth and thus give rise to so-called earth currents. These earth currents will flow through the earth, as shown by arrow 10, and on to the pipe or cable 6 at points where the pipe is of a lower potential or negative to the earth. If all sections of the pipe 6 are negative to earth, these earth currents would then flow along the pipe and then leave the pipe over the conductor 7 by which it is bonded to the negative bus of the generator 3 at the power house. However, all sections of the pipe 6 may not be negative to earth and a section of the pipe, such as A,

between dotted lines 8 and 9, may be posi- Which had entered the pipe at other sections H thereof and were flowing along the pipe, would, when they reached section A, escape from the pipe and lie W back into the earth. Accordingly there would be a tendency for electrolytic corrosion to take place at section A. M j

Inaccordance with the arrangements of this invention, the wire o is bonded to a ,section, such as C, of the pipe,which is of L positive potential with .resuoect to that of the pipe at A and is then burielin the ground in the vicinity of sectionA. At section B the pipe 6 maybe bonded by conductor 7 to thenegative bus of generatorfi and accordv,ingly at section the pipe ,will be of a negative potential with respect tothe earth. As the pipe is bonded ,to the, negative bus of the generator 3, the earth currents which accumulate on the pipe atpoints beyond A, such as between C and A, will tend to flow toward B. In other worrlsthei'e will be a potential drop between C and Bend a point,

such as C, as it is farther along the pipe than point Atwill have, a higherpotential than or be Jositive with resoect to A. Accorch ingly the wire ,5,will have a potential higher than or positive w th re spect to the pipe. at A and when buried in the earth at A it will a have the efiect of )ullinc u) or raising the i l i U 3 potential of the earth in which it is buried to a potential h gher than or positive with respect to the pipe at A. In other words it I will have the effect ct raising the earth potentia-l at A to approximately that of the iie at C which as has been Jointed out, w

is higher than at A. This will result because the fall of potential :trom section Cto section A will be greater along the pipe than along the wire 5. Accordingly as thepej tential of the earth at is now positive with respect to or higher than that of the pipe at A, the earth currents will not escape from the pipe at A but will remain on the pipe and will return over conductor 7 to, the generator In this manner electrolytic corrosion at section A may be prevented. i The arrangements of this invention p re-l sent many improvements over tormeran rangements, which are designed to mitigate electrolytic corrosion vand which operate on the principle of raising theearth potential about thefarticle, rather than by lowering V the potential of the article itself, The auxilia ry conductor, such as 5,,which is buried in the earth and serves to raisethe earth potential at points where it is desired to PI'B-I vent the earth currents from escaping from the article, may be bonded to a positive sec- ,tion of the article, such as the pipe, as Qshown; and it is not necessary to supply a separate source of current and to connect to the positive pole of such the wire 5'. The pipe, or metallic article, may be bonded as shown by conductor 7 directly to the negative bus o'tthe generator, such as 3, at the powerhouse. In this instance too the provision of a separate source of current to which the pipe may be bonded is avoided. The earth potential, in other words, may be raisedat desired points by thearrangements of this invention without the provision of a special protective circuit tor this purpose but rather by means which are much simpler in construction, of a, great c eal less expense, which are adapted to beinstalledwith ready facility, and ,whichare more eliicient than former arrangements. 'lhedevice of this invention presents the further advantages that the auxiliary wire, such as need only be buried in theparticular localities where it ,is desired to prevent electrolytic corrosion and need not be installed atall points where the metallic article is ii the vicinity of the track. Furthermore the point at which the article or pipe may be bonded to the negative bus of the powerhouse, as shown by 7 ,may be arbitrarily chosen, without regard to the location of the positive areas of the pipe Tliis presents theadvantage that this point may be conveniently chosen in a lo cality close to the power plant.

While the metallic article, which is embedded in the groun dand subject to electrolytic corrosion, has been. illustrated as a pipe or cable, is understood that the invention may operate equally. well with other types of articles which are subjected to the electrolytic effects of earth currents. Accordingly while the invention has been disclosed in certainspecific forms which are deemed desirable, it is understood that it is a capable of embodiment in many and widely varied forms without departing from the spirit of the invention as defined in the appended claim.

What is claimed An electrically operated railway system, ametallic article buried in the ground in the vicinity of the tracks of said system, means to connect said article to tlie negative pole of the generator of said system, and a conductor buried in the ground in the vicinity of a section of said articlewhich would normally haveapotential positive to earth, said conductor being connected to a section of said article havinga potential, positive to the potential, of said firist in entional section of saidarticle, whereby the earth potential in the yicinity of said firstnientioned section of saidfarticleuwillberaised soia's to be posi tive with respect to said first mentioned a section 1 f said article.

' In testi'n onyf whereof, I have signed my nanieto; this specification this twenty-fourth day ol April, 1922. a a I GEORGE G. JONES. 

